Torque transmission device useful as a fixed constant velocity ball joint for drive shafts and method for producing such a joint

This application is a continuation of international patent application no. PCT/DE2007/001183, filed Jul. 5, 2007 designating the United States of America and published in German on Jan. 10, 2008 as WO 2008/003303, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application nos. DE 10 2006 031 002, filed Jul. 5, 2006; DE 10 2006 037 847, filed Aug. 12, 2006 and 10 2007 030 898, filed Jul. 3, 2007.

The invention relates to a torque transmission unit having at least one component for transmitting torques via each of two functional areas formed onto the component and causing the torque flow by a formfitting engagement with other elements, at least one of the two functional areas being constructed as a profile, such as longitudinal teeth.

Torque transmission units of this type are disclosed, for example, in U.S. Pat. No. 6,872,143 (=DE 102 20 715) in connection with side shafts and in US 2006/0014587 (=DE 102 37 172) in connection with longitudinal shafts.

In U.S. Pat. No. 6,872,143, two such components are provided for each of the fixed, constant velocity ball joints provided on both ends of the side shaft, on each of which different functional areas formed onto the particular component are provided, which cause the torque flow by formfitting engagement and one of which is constructed as longitudinal teeth.

One component is the joint external part, whose one functional area causing the torque flow by formfitting engagement is a connection pin having formed-on longitudinal teeth, which is provided on the joint external part, and whose other functional area transmitting the torque are the raceways in the joint external part for the balls of the joint.

The second component also having two functional areas for transmitting torque is the joint internal part having formed-on longitudinal teeth in the central internal area as one functional area and having formed-on ball raceways of the joint internal part as the other functional area.

In the torque transmission unit according to US 2006/0014587, a component having two functional areas for transmitting torque is also provided for each of the three joints contained therein, namely a joint internal part having formed-on longitudinal or spline teeth as one functional area and formed-on ball raceways as the other functional area in each case.

In components of this type, i.e., joint parts, for example, the internal teeth are typically broached and the external teeth are typically produced by pounding, milling, or rolling, and the ball raceways are produced by machining or by a non-chip-forming or chipless technique.

To be able to transmit sufficient torque, at least the ball raceways are hardened. These raceways may be inductively hardened and the remaining area, i.e., also the longitudinal teeth, may be left at the basic hardness. This is advantageous for producing longitudinal teeth, but does not permit the high torque values to be transmitted and the desired service life to be achieved, which are required in many cases.

The inductively hardened ball raceways, for example, must be machined hard because of the distortion occurring upon partial hardening after the hardening to achieve the acquired precision, i.e., hard milling or grinding must be performed.

Another known possibility is to first manufacture the teeth in the soft state, to case-harden the entire part, i.e., having formed-on longitudinal teeth, which results in hardening distortion of both the teeth and also the spline teeth, however, which may only be remedied in the longitudinal teeth with additional great effort, namely by hard broaching in the hard layer using corresponding suitable, but costly special machines and tools, for example.

The present invention was based on the one hand on the object, in torque transmission devices of the type described above of obtaining high strengths and thus ensuring the transmission of high torques at high precisions, i.e., optimum fit and optimum true running, as well as allowing cost-effective and efficient production, and increasing the service life of assemblies, machines, and devices equipped with components of this type.

Furthermore, the invention relates to torque transmission devices, such as fixed, constant velocity ball joints as opposed track joints having

a joint external part having external tracks,
a joint internal part having internal tracks,
torque-transmitting balls, which are accommodated in track pairs made of external tracks and internal tracks,

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Torque transmission device useful as a fixed constant velocity ball joint constructed as an opposed track joint and method for producing such a joint
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Propshaft with constant velocity joint attachment
Industry Class:
Rotary shafts, gudgeons, housings, and flexible couplings for rotary shafts

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